Home Theater Equipment Review

April 1999

Phase Technology PC Surround Speaker

Getting in phase

I have always been of the opinion that you shouldn't cheap out on surround speakers because good home theater is not possible without good surround speakers. My philosophy is that if a pair of speakers is not suitable for use in a good two-channel system, they aren't suitable for use as surround speakers either. Over the years, I have utilized many pairs of loudspeakers as surrounds for home-theater use. Each pair was progressively better and more expensive than the pair that they replaced. All of these have been direct-radiating bookshelf speakers designed for stereo use, and I enjoyed my time with all of them. When I was given the opportunity to evaluate the Phase Technology PC Surround loudspeaker, I was curious to see how a dedicated surround speaker would fare in my home-theater setup.

A few years ago, when Lucasfilm began certifying home-theater equipment for their THX program, they required that surround loudspeakers be dipolar in design to receive certification. Dipolar loudspeakers have a more diffuse soundfield than conventional direct-radiating speakers and thus are considered more desirable by THX for surround-speaker applications. This resulted in a proliferation of dipolar surround designs from many manufacturers -- some that were THX certified and some that were not. The Phase Technology PC Surround is a bit of a hybrid design, which I will get to later, but it follows most of the same design principles as other dedicated dipolar surround loudspeakers.

Most conventional loudspeakers feature direct radiating designs that utilize drivers mounted on the front of a sealed cabinet that radiate sound more or less directly at the listener. Dipolar designs radiate sound simultaneously in both a forward and backward direction, but out of phase with each other. A variation of this design is the bipolar loudspeaker, which is essentially the same as a dipole except that the sound radiates in phase in both directions. Companies like Martin-Logan and Quad have been manufacturing electrostatic loudspeakers that are inherently dipolar, and Mirage developed the M-1 bipolar loudspeaker for stereo use in the mid ‘80s. However, dipolar and bipolar speakers designed specifically for use as surround loudspeakers in home-theater applications are a fairly recent development. Although Phase Technology is not known for dipolar or bipolar designs for stereo use, they have been manufacturing loudspeakers for several decades and currently have several full lines of stereo and home-theater speakers.

Design phase

As I mentioned, the PC surround is a hybrid design. It is a dipolar speaker of the non-THX variety as well as being bipolar in design. How is this possible? Well, the PC Surround features a switch that enables you to alter its radiation pattern from dipolar to bipolar mode depending on your preference. Each PC Surround utilizes five drivers -- two 1" soft-dome tweeters, two 4" polypropelene midranges, and a single 6.5" solid-piston woofer. One tweeter and one midrange are arranged in a vertical array on one of two baffles that are angled slightly inward on either side of the speaker cabinet, and the single woofer fires directly into the room on the side that is opposite the wall. Actually, if you think about it, only the tweeter and midrange sections will have a dipolar or bipolar radiation pattern, and the single woofer will presumably be in phase with one of the pairs of tweeters and midranges. Each speaker is 14 3/4"H by 14 3/4"W by 6"D and weighs in at a hefty 16 pounds. Like most surround loudspeakers, the PC Surround is designed to be placed against a side or rear wall. Because I do not have proper side walls in my room, I mounted the speakers on the rear wall, about a foot behind the couch and approximately two feet above the listener’s position. The PC Surrounds performed well there, and I did not experiment further with positioning. The owner's manual recommends placing the PC Surrounds slightly above the listening position and to the sides or rear of the room, but gives little advice on speaker placement otherwise.

The tweeters feature a "proprietary Unicell acoustic treatment" that looks suspiciously like neoprene foam. Each tweeter is surrounded by a circular piece of this material that is flush-mounted on the baffle to reduce unwanted cabinet diffractions. Other manufacturers utilize strips of foam or pieces of felt to reduce diffraction, and these materials can be purchased as "tweaks" to modify speakers that do not employ them. I can attest to the usefulness of these devices as I use a pair of them on the already excellent NHT Super Zeros and find that the imaging is improved, if only slightly.

The PC Surround speakers are solidly built and have removable end caps and cloth socks that cover the drivers. The color of the speaker is determined by the color of the end caps and sock, and these are available in either black or white. Phase Technology provided me with one in each color -- presumably to demonstrate the two different finishes. While these are somewhat nondescript speakers, they look a lot better than most surround speakers do. The end caps are finished in a textured laminate that is quite attractive, and the angled baffles and cloth coverings give the speakers a softer, more elegant look. Although I thought it looked strange at first, I actually preferred the white finish because of the way it blended with my off-white walls.

The PC Surrounds are rated with a sensitivity of 89dB, an impedance of 6 ohms, and a frequency response of 55Hz to 22kHz. Minimum amplifier power is recommended at 20 watts. Judging by the specifications, these should not be particularly difficult speakers to drive. This is a good thing considering the sound levels present in the surround channels of many recent digital soundtrack mixes. I informally measured the bass response of these speakers in my two-channel rig, which resides in a different room from my home-theater system. The response was down about 3dB below 55Hz, with usable bass down to 35Hz or so judging from what my trusty old Radio Shack SPL meter was reading and what I could hear and feel.

Phasing in the new

I was immediately impressed with these speakers. The sound coming from the rear of my room had a solid character and depth that was not normally associated with surround speakers. In many respects, the sound was more of what might be expected from a high-end pair of stereo speakers. It no longer seemed to be coming from a single source, but rather from a continuum stretching from one speaker to the other. At times, the sound seemed to emanate from in front of the speakers and to the sides of the room.

Although the owner’s manual gives a few tips on positioning, it does not mention the switch that changes the speaker’s operation from dipolar to bipolar mode at all! The only reference to the switch is in a promotional pamphlet that is provided along with the manual. I experimented with the switch in both the dipolar and bipolar position and found very little difference. I thought that there might be a little bit more bass with the switch in the bipolar position and that the sound was just slightly more expansive when the switch was in the dipolar mode. However, the differences were subtle and very dependent on the source material. Being somewhat of a bass freak, I ran the speakers in bipolar mode for most of my listening and placed my processor's surround speaker setting to "large" so that they were running full range. I feel that good surround speakers should be nearly full range with response down to 50Hz or so -- similar to good bookshelf speakers. With nearly full-range bass coming from both the main and surround speakers, the low-end response in the room really seems to smooth out, giving you that "big" sound that is the signature of good home theater. This was particularly evident when I played the "Cairo" Dolby Digital trailer from the DVD Spectacular [Delos DV 7001 DVD], which has massive amounts of bass in the surround channels and provides a solid sonic foundation to this excellent demo clip.

The sound of the PC Surrounds can best be described as enveloping, with sound coming from behind and to the sides of the listener. There was very little distinction between the soundfield in the back of the room with that in the front of the room. With lesser surround speakers there is usually a very distinct differentiation in the sound as it moves between the front and back hemispheres of the room. The soundfield was now much more homogeneous from front to back. There was also good depth with directional effects seeming to originate from all around the rear half of the room. The PC Surrounds acquitted themselves well with Prologic, Dolby Digital, and DTS source material.

Dolby Prologic laserdiscs that heavily exploited the mono rear channel were well rendered. The chapter titled "Bad dreams; a new look" on The Fugitive [Warner 21000 LD] during which Kimble dreams of his wife was truly holosonic, with wraparound surround effects. Interior scenes in Terminator 2 [Carolco/Live LD68952-2WS LD] at the Pescadero State Hospital (chapters 24 to 26) had excellent low-level detail that highlighted the subtle foley effects and music soundtrack, and which provided a great deal ambience. The effect was creepy and absorbing.

Not only were the PC Surrounds enveloping, but they also presented plenty of detail with excellent delineation of individual effects, even during very complex passages. In chapter 24: "Alley Trapped" of The Replacement Killers [Columbia 21629 DVD], every round that Chow Yun-Fat fires from his Barettas is followed by a very faint but distinct "swooshing" sound that originates from the surround channels. The PC Surrounds were able to extract tiny details like this from all manner of complicated mixes.

Dolby Digital and DTS soundtracks often require full-range response in surround loudspeakers and high power handling capabilities. The PC Surrounds handled every surround torture track that I threw at them, and none was more demanding than the Imax film Super Speedway [Image ID46220W DVD]. The roar coming from the Ford Cosworth engine of Michael Andretti’s car as it traveled from the front of my room to the back was throaty, rock-solid and really loud, with no obvious signs of distortion. I have never heard the ultra aggressive surround mix of Super Speedway sound so good.

Apples and oranges

The PC Surrounds were expansive, with deep bass, and possessed exceptional detail. Compared to my reference NHT 1.5s, they fared very well. The Phase Techs have the advantage of being dedicated surround loudspeakers and having been designed that way from the ground up. Although the NHTs are excellent stereo speakers and also make good surround speakers, they simply could not match the Phase Techs in immersing the listener in an enveloping rear soundfield.

For instance, the wind in the opening credits of The Sweet Hereafter [Alliance/New Line N4654 DVD] is all around you, as are the deep, rumbling effects present in the opening credits of Gattaca [Columbia 82649 DVD]. The surround ambience of disc after disc was noticeably better with the Phase Techs. However, the NHTs seemed to have slightly deeper, tighter bass. The bass in the surround channels of the previously mentioned "Cairo" Dolby Digital trailer was just a little bit looser with the Phase Techs. The NHTs were also slightly better on music material such as in the opening credits of Desperado [Columbia/Tri-Star 11656 LD] where Antonio Banderas gives a rousing performance of "Morena de mi Corazon." The guitar chords were cleaner and had more natural timbre. Despite this, there was no problem with the musicality of the Phase Techs during the Diva scene in The Fifth Element [Columbia/Tristar 82409 DVD], and their added ambience and envelopment made for a more satisfying listening experience.

During calibration of the system, I noticed that the Phase Techs required the surround levels of my processor to be set two dBs higher than with the NHTs. Although the Phase Techs were not a particularly difficult speaker to drive, they will certainly benefit from having large amounts of high-quality amplification to show off their capabilities -- like most audiophile loudspeakers. The 125Wpc Carver AV-705x that I used during most of my evaluation had no problem in handling the Phase Techs, but I am confident that they could be adequately driven by most of today’s Dolby Digital-equipped receivers that provide equal power to all five channels. As a matter of fact, I was also able to achieve good results with the Panasonic Technics SA-AX6 receiver.

Phase inversion

So am I sold on dipolar and bipolar speakers such as the Phase Techs for home-theater surround applications? You betcha. This is not to say that direct-radiating designs cannot function well as surround speakers too. I will continue to use speakers like the NHT 1.5s as surrounds in home-theater systems, but dedicated dipolar or bipolar surrounds make a lot sense. Their enveloping soundfield is very enticing, and I did not notice any lack of imaging capabilities. I actually noticed very good positioning of effects throughout the rear soundstage that was not present with my NHTs.

At $700 USD, the Phase Technology PC Surrounds are not cheap. In fact, they cost more than what a lot of people might be willing to spend on main speakers. But they are the best surround loudspeakers that I have had in my system. If you are serious about home theater, these speakers are definitely worthy of your consideration. If you already own main and center-channel speakers from one of Phase Technology's highly regarded product lines, I would not hesitate in recommending these top-of-the-line surrounds to complement your system.

...Roger Kanno
roger@soundstage.com

Manufacturer:
Phase Technology Corporation
6400 Youngerman Circle
Jacksonville, FL
Phone: 1-888-PHASE TK
Fax: (904) 771-7793

Website: www.phasetech.com 

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